1. Field of the Invention
The present invention relates to a torque calculation method, a calculation device and a calculation program for calculating the rotational torque induced between inner and outer rings in a four point contact ball bearing, which are all applicable to the four point contact ball bearing assembly of a kind used in, for example, a slewing bearing assembly, used in a wind power generating equipment for yawing or a blade assembly, or a slewing bearing assembly used in medical equipments such as a CT scanner.
2. Description of Related Art
In the bearing assembly for use in the wind power generating equipment or for medical equipment in, for example, the CT scanner, the single or double row four point contact ball bearing assembly has hitherto been employed. The slewing bearing assembly having the four point contact ball bearing structure has long been employed in applications such as a slewing unit in hydraulic excavators and cranes. Although in those applications, for a given rotational torque necessary to slew the bearing assembly, a drive device having a sufficient (torque) capacity has been employed, demands have now been increasing in the market to downsize, and promote the efficiency of, the wind power generating equipment and, therefore, it is an important key issue to accurately comprehend the rotational torque.
In these days, the following equation for calculating the rotational torque in the slewing bearing assembly is currently employed:
<Conventional Calculation Equation>T=μ×dm/2×Poa wherein T represents the rotational torque [kN·m], μ represents the coefficient of friction, dm represents the ball PCD [m], and Poa represents the static equivalent axial load [kN].